This invention relates to the container art, and more particularly a paperboard tray formed from a unitary blank of stiff, resilient and foldable sheet material such as paperboard. In forming paperboard trays, whether their sides and edges are vertical or are slanted either inwardly or outwardly, it has been customary in the art to use an adhesive to join the end panels of the tray to the tray side panels. Typically, either the side panels, or the end panels, or sometimes both, will have extensions termed web panels which overlap with the end of a neighboring panel, with these overlapping portions being glued together to make the tray rigid and maintain it erected.
While such constructions are usually satisfactory, there are certain instances wherein the use of an adhesive is undesirable, such as when the tray is used to serve a food product. In such situations, it would be desireable to effect some other means of locking the ends of the side and end panels together to thereby maintain the tray in an erected or set up configuration and thereby impart the desired rigidity to it. The possibility of contamination of food by the adhesive usually exists no matter how slight and accordingly not all of the known tray constructions are suitable for a food use.